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regex to match an ip

Terminal - regex to match an ip
echo 254.003.032.3 | grep -P '^((25[0-4]|2[0-4]\d|[01]?[\d]?[1-9])\.){3}(25[0-4]|2[0-4]\d|[01]?[\d]?[1-9])$'
2009-09-17 12:59:44
User: foob4r
Functions: echo grep
0
regex to match an ip

This obey that you don't match any broadcast or network addresses and stay between 1.1.1.1 - 254.254.254.254

Alternatives

There is 1 alternative - vote for the best!

Terminal - Alternatives
perl -wlne 'print $1 if /(([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5]))/' iplist
2009-09-17 16:14:52
User: salparadise
Functions: perl
-1

if you want to only print the IP address from a file.

In this case the file will be called "iplist" with a line like "ip address 1.1.1.1"

it will only print the "1.1.1.1" portion

echo 127.0.0.1 | egrep -e '^(([01]?[0-9]{1,2}|2[0-4][0-9]|25[0-4])\.){3}([01]?[0-9]{1,2}|2[0-4][0-9]|25[0-4])$'
2009-09-17 17:40:48
User: arcege
Functions: echo egrep
-1

Handles everything except octets with 255. Ran through ip generator with variable octet lengths.

echo "123.32.12.134" | grep -P '([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])'
2009-09-17 12:17:32
User: KeePon
Functions: echo grep
-2

regex to match an ip

Know a better way?

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What others think

Doesn't handle 127.0.0.1, which is a valid address.

Comment by arcege 253 weeks and 4 days ago

How do you know what the network and broadcast addresses are without knowing the network mask? If you're on 10.0.0.0/8, then 10.0.0.255 and 10.0.1.0 are both valid addresses.

Comment by andrew112358 253 weeks and 4 days ago

The combo of the leading ^ and the trailing $ will force the regex to match an IP address on a line all by itself, so this will not match IPs embedded in text.

Comment by bwoodacre 253 weeks and 4 days ago

ok u'r right @andrew112358 i only thought about /24

Comment by foob4r 253 weeks and 3 days ago

Your point of view

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